Stevenson begins his short book Seven Theories of Human Nature with an overview of philosophy by way of a comparison of Marxism and Christianity. These two (often competing) worldviews have some things in common while they are diametrically opposed on the essentials. For example, Marxism doesn't just differ on Who God is, but instead says there is no God at all. One of the primary ways that one's sense of power and authority, personal behavior towards power and authority, and sense of justice or righteousness is shaped or formed by Stevenson's book is by a sense of the great conflict between ideas. Rather, people have ideas, and people have conflicts with each other because of the ideas they have, because promotion of a particular idea becomes more important than promotion of a particular person.
Plato taught the existence of "absolute forms" and compares these forms to the development of Euclidean geometry (29-30). In Euclidean geometry there are straight lines, even curves, and perfect circles, unlike nature. The facts of nature were seen as deviations from the rule of perfection that Plato felt must have existed in the absolute form. When Plato brought this to bear on human nature, he saw two principal facets of each human: the appetite and reason. The appetite drives a person to eat, which is good, but also drives a person to overeat for the sake of sensory stimulation. Plato then decided that reason was more perfect than appetite, so in his Republic the rule of the government is given to the philosopher kings who best exercise reason in their decisions.
On page 33 Stevenson quotes Plato: "There will be no end to the troubles of states, or of humanity itself, till philosophers become kings in this world, or till those we now call kings and rulers really and truly become philosophers, and political power and philosophy thus come into the same hands." A person's actions regarding this is then to work for putting philosophe...